# Fluid Dynamics Bernoulli

## Main Question or Discussion Point

Can someone smarter than I, please express p1 and p2 in terms of f, or v and r?

The pump pushes out water at f rate which creates velocity v in the bigger pipe. When the water comes to the restriction velocity increases while flow rate is conserved. Bernouli tells us that the change in velocity requires a change in dynamic pressure to conserve the energy. However, I can't seem to figure out how dynamic pressure translates into the static pressures which are measured by the "head" which would be developed in both pressure measure tubes. I can't seem to translate the negative pressure changes given by Bernouli equations into dynamic and total pressures which would appear in the measure tubes. Tube on the left would have a higher water level than the tube on the right.

If someone can, please show me. I am a computer programmer writing a liquid simulator for my employer for a very specific application. Thank you so much for anyones help.

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Can someone smarter than I, please express p1 and p2 in terms of f, or v and r?

The pump pushes out water at f rate which creates velocity v in the bigger pipe. When the water comes to the restriction velocity increases while flow rate is conserved. Bernouli tells us that the change in velocity requires a change in dynamic pressure to conserve the energy. However, I can't seem to figure out how dynamic pressure translates into the static pressures which are measured by the "head" which would be developed in both pressure measure tubes. I can't seem to translate the negative pressure changes given by Bernouli equations into dynamic and total pressures which would appear in the measure tubes. Tube on the left would have a higher water level than the tube on the right.

If someone can, please show me. I am a computer programmer writing a liquid simulator for my employer for a very specific application. Thank you so much for anyones help.
Question like this will be closed if you do not show your work.

I'm not sure what adversity you feel you are protecting the forum from, but I worked on this problem all work day. I must be missing something stupid and simple, but I can't find it and I hope someone knows what I am missing. I attached pics of all my work today

http://jerrywickey.com/emails/IMG_00010.JPG http://jerrywickey.com/emails/IMG_00011.JPG

Last edited by a moderator:
Nidum
Gold Member
The two vertical tubes are really just pressure gauges . Omit them initially and solve the primary problem of flow in the two horizontal pipe sections . When you've done that you can go back and find the column heights in the vertical tubes which will balance the calculated pressures in the horizontal pipe sections .

Yes they are, but I don't know how to solve for pressure absolute or gauge given flow rate. I can find only the the pressure differential which is a negative value. I need to know the gauge pressure. i.e. How high will the pressure push the water in the vertical tubes.

Nidum